function $(id){
    return typeof id==='string'?document.getElementById(id):id;
}
window.onload=tab;
function tab(){
    //当前高亮显示
   var index=0;
   var timer=null;
   //获取所有的页签
   var lis=$('notice-tit').getElementsByTagName('li');
   var divs=$('notice-con').getElementsByTagName('div');
   for(var i=0;i<lis.length;i++){
    lis[i].id=i;
    lis[i].onmouseover=function(){
        clearInterval(timer);
       changeOption(this.id);
    }
    lis[i].onmouseout=function(){
        timer=setInterval(autoPlay,2000);
        }
   }
   //添加之前先清空定时器
   if(timer){
    clearInterval(timer);
    timer=null;
   }
   //添加定时器
   timer=setInterval(autoPlay,2000);
   function autoPlay(){
     index++;
    if(index>=lis.length){
        index=0;
    }
    changeOption(index);
   }
   function changeOption(curIndex){
    for(var j=0;j<lis.length;j++){
        lis[j].className='';
        divs[j].style.display='none';
    }
    //高亮显示当前内容
        lis[curIndex].className='select';
        divs[curIndex].style.display='block';
        index=curIndex;
   }
}